Objective: To assess the validity of intraoperative auditory brainstem response in infants and difficult-to-treat older children.
Study design: Case series with chart review.
Setting: Tertiary-level children's hospital.
Subjects and methods: Twenty-six patients were identified (mean age, 20 +/- 18 months) who underwent both intraoperative auditory brainstem response (ioABR) testing and a follow-up hearing evaluation at five (standard deviation 4) months. Ears were analyzed separately for mean threshold change, and a sub-analysis was performed accounting for the presence or absence of fluid at the time of surgery.
Results: A paired t test analysis indicated a statistically significant difference at 1 kHz. There was not a statistically significant difference between the two groups with click or 4-kHz testing. Fifteen ears (58%) at 1 kHz and 17 ears (49%) at 4 kHz frequencies, however, improved by 10 dB or more; 67 percent and 65 percent of these ears, respectively, had middle ear fluid intraoperatively. Eight ears (35%) in the click ABR group had a similar improvement, four of which had fluid at the time of surgery. Four ears in the 1-kHz (11.5%), in the 4-kHz (11.4%), and in the click ABR group (17.4%) demonstrated a 10-dB or worse threshold. The range of the discrepancy varied from a worsening in thresholds up to 20 dB and improvement in thresholds up to 45 dB.
Conclusions: We observed a significant discrepancy between ioABR and follow-up hearing thresholds. If ioABR indicates a hearing loss, audiologic testing should be performed at least several weeks later to confirm the results.